Technical Field
The present invention relates to the field of glasswork and processing, and in particular, to a curved reflective mirror applied in the field of solar energy and a manufacturing method thereof.
Related Art
At present, in many industrial apparatuses, especially in a solar energy light concentrating system, various light concentrating reflective mirrors of different shapes are often used. The light concentrating reflective mirrors are mainly classified into a trough parabolic reflective mirror, a curved parabolic reflective mirror, a curved and spherical reflective mirror, and so on.
In solar energy light concentrating applications, the requirements on optical properties of a reflective mirror are usually lower than those on a general optical lens. Therefore, a conventional mirror surface grinding method is not used in manufacturing of a solar energy reflective mirror surface, so as to reduce the manufacturing cost.
For an existing curved mirror, a manual gluing method is usually adopted to stick multiple small and thin glass lenses to a large sheet of curved glass. For this kind of curved mirror manufactured by distributing the small and thin glass pieces on a curved mirror of an adhesive structure, the mirror surface has poor light concentrating performance and low mirror surface reflection precision, and mostly air bubbles exist between the small and thin glass pieces and the glue. Therefore, weather resistance and corrosion resistance performance are also poor, which affect the service life. In addition, to manufacture a curved mirror of this structure, first, a large and thin glass mirror needs to be cut into multiple small pieces, and then the small glass pieces are stuck to a large sheet of curved glass, which involves a large number of complicated procedures, requires much labor and time, and makes manual operations heavy and cumbersome, thereby directly leading to low product output and a high manufacturing cost and making the curved mirror unsuitable for large-scale serialized production. In addition, if the glue is not uniformly applied, a surface appearance of the reflective mirror may be bad and the refection precision may become low, so that a high concentration ratio cannot be achieved and the product quality cannot be ensured.
In a general situation, a curved reflective mirror is obtained by deforming a flat mirror or flat glass. Two types of formation processes exist for the curved reflective mirror, one is a high-temperature thermal deformation manufacturing method, and the other is a mechanical cold deformation manufacturing method.
In the high-temperature thermal deformation manufacturing method, glass is first heated to a softening state and is then shaped in a mold. For a formed glass blank, a reflecting layer is coated thereon, and a protective layer is sprayed thereon. The manufacturing cost of this process is quite high.
In the mechanical cold deformation manufacturing method, a flat glass mirror is closely pressed against a curved surface mirror holder in a mechanical crushing manner, so that the glass mirror is mechanically deformed according to a curved surface shape of the mirror holder, and the mirror and the mirror holder are fixed through an adhesive or in a mechanical manner to form a curved reflective mirror. For a curved surface of a curved reflective mirror, the manufacturing cost required in this manner is lower than that required through the high-temperature deformation method, but the mirror holder and the curved reflective mirror have inconsistent temperature expansion coefficients. In addition, for the curved reflective mirror manufactured through this mechanical cold deformation manufacturing method, since an adhesive or a mechanical manner is used for fixing the mirror and the mirror holder, a protective paint on the back of the mirror is exposed to air. If this kind of reflective mirror is used outdoors for a long time, a reflecting layer may corrode, which shortens the service life of the reflective mirror.
In a Chinese Patent Application with the patent number 200810105690.1 and entitled “Curved Reflective Mirror Having High Mirror Surface Reflection and Manufacturing Method Thereof”, curved glass formed by using a layer of curved glass and a layer of flat and thin glass mirror is disclosed. However, the curved glass used in the solution is still obtained by using a hot bending technology, and the cost is high.
In a Chinese Patent Application with the patent number 200910302460.9 and entitled “Method for Manufacturing Curved Reflective Mirror Used for Solar Heliostat”, a method for manufacturing a curved reflective mirror is disclosed. In this patent application, each reflective mirror is formed of a flat reflective mirror and a mirror holder that are fixed through high-temperature heating. However, since the mirror holder and the curved reflective mirror have inconsistent expansion coefficients, the mirror holder and the curved reflective mirror contract inconsistently after being cooled, so that the solidification effect is weakened, and an adhesive failure phenomenon may occur in an application process of the reflective mirror. In addition, in a procedure of manufacturing the curved reflective mirror, this method involves a high vacuum pressure, so the structure of the mirror holder requires high strength; otherwise, the precision of a curved surface is affected. Since each reflective mirror demands a mirror holder of high strength and high precision, it is unfavorable for large-scale production and control of the cost.